Multiple piston elliptical fluid cylinder



May 9, 1961 M. M. SEELOFF MULTIPLE PISTON ELLIPTICAL FLUID CYLINDER Filed July 15, 1958 R m H W W O m A E E S u M. f m w M w H H N- @N 7 on 3 llllllllllllllllllllllllll ll llllllll II N mu m hm w Hm O United States Patent O MULTIPLE PISTON ELLIPTICAL FLUID CYL NDER Melvin M. Seelofi, Warren, Ohio, assignor to The Taylorggliifield Corporation, Warren Ohio, a corporation of Filed July 15, 1958, Ser. No. 748,628 1 2 Claims. (Cl. 121-38) the actuating means in many types of apparatus. In many instances a high force applying fluid cylinder of small size and dimensions is required since the space and clearances provided for mounting the cylinder are quite restricted due to other considerations. However, cylinders constructed in accordance with prior art teachings'havenotbeen able to fulfill these conditions-small size and high:

force applying capability-and this has somewhatlimited the utilization of fluid-cylinders where they otherwise might be advantageouslyemployed.

In accomplishing the above object the fluid cylinder of the present invention is elliptical in cross sectional shape and has a plurality or multiplicity of pistons. The ellipti; cal shape of the pistons and the number thereof provide large surface areas in order that high forces maybe dc vcloped while the overall size of, the fluid cylinder is ex-- tremely sm'all. p

A further object of the invention is to provide a fluid cylinder wherein thepiston rod does not rotate but is always retained in one position with respect to the cylinder housing. The elliptical pistons guide and prevent rota-j tion of the piston rod and in this manner guides, ways,

etc. for guiding the movement of the driven member at-.

tached to the piston rod are completely eliminated.

Another object of the invention is to provide a multiple piston elliptical fluid cylinder which is characterized by its extreme versatility and flexibility and is. adapted to be tailored for each individual applicatiom. The fluid cylinder of the present invention comprises a plurality of identical cylinder wall' elements, cylinder spacer elements.

and elliptical pistons which areasseinbl'edin stacked re-- lation and the fluid cylinder can. be constructed to have eiractly the force applying capability'required; depending spacer elements and upon 'the' numberof wall elements,

elliptical pistonsemployed. 7 V r Yet a further objectjo'f the present invention is to pro vide a multiple "piston elliptical fluid cylinderhaving the characteristics outlined above which embodiesimproved featuresfof construction; Of particular importance are the use of a common piston rod which'is tapped to pro vide fluid passageways, the'siinple and identical construetion of the various elements and parts; the'various fluid sealingfmeans employed, the mounting means for attach- -ing the elliptical pistons to'the piston rod and the guiding means-for guiding the piston rOdall of which provide an improved fluid cylinder of the small size which is. easily and inexpensively manufactured and assembled. j 1 These, as well 'as' other objects and advantages of the.

' such that this portion does not interfere withlongitudinal ,,movement in an easy manner while yet ing drawing wherein there is disclosed an illustrated em bodiment constructed in accordance with the teachings of the present invention.

In the drawing: a

Figure 1 is a longitudinal sectional view of a multiple piston elliptical fluid cylinder constructed in accordance with the teachings of the present invention;

Figure 2 is a sectional view taken along the section line lII[ of Figure 1; and

Figure 3 is a sectional view taken along the section line IIIIII of Figure 1.

Referring now to the drawing, there is shown ple piston elliptical fluid cylinder which comprises a main cylinder portion generally designated by the reference numeral 10 and front and rear cylinder heads 11 and 12, respectively, which are received on opposite ends of the main cylinder portion10. The main cylinder, portion 10 is assembled from a plurality of cylinder wall elements 1 3 and cylinder spacer elements 14. Each of these elements is shaped with truncated side edge portions (see Figures 2 and '3) so that the main cylinder portion is generally elliptical in cross section throughout its length. The front and rear cylinder heads 11 and 12 are rectangular in shape and receive the ends of four longitudinaly extending tie rods 16 adjacent the corners thereof.

The tie rods extend the length of the main cylinder portion between the front and rear cylinder heads and retain the heads, cylinder spacer elements and cylinder wall elements in axially aligned assembled relation. It will be noted that the shape of the main cylinder portion is passage of the four tie rods 16. a

Each of the cylinder wall elements 13 is a hollow or annular sleeve-like member having an appreciable axial dimension which is machined or formed to define anelliptical inner surface 17.; Separating the adjacent cylinder wallelements 13 are the cylinder spacer elements 14 which have elliptical-notches 18 around the edges and on both sides thereof that serve as seats for the ends of the generally elliptical,, ;ylinder wall elements 13. The, cylinder spacer elements '14 are centrally 'apcrtured at 19'and circular seating grooves are provided intermediate 'the ends of these apertures, Received and mounted in positive fluid rtight :seals are provided beetwen opposite. sides of the cylinder. spacer elements 14. The spacer elements '14 areeach providedwith a right angled passageway "22 extending-between the. back-1sides and. the side edges thereof which passageways define a plurality of relief passageways whose function will be hereinafter more fully explained. r

As indicated*above;" the main cylinder portion 10- comprising 'the' alternate stacked wall elements '13 and spacer elements. 14'is held in tight'assem'bled relation by the tie rods 16 extending between the front and rear cylinder heads 11 and 12. "Therear cylinderhead 12 is 7 generally rectangular in crosssection and is formed with an inwardly directed elliptical flange-24 which receives the outer end of the rearmost cylinderwall-element of invention, will become more readily apparent upon con sideration of the following specification and accompany- Patented May 9, 196;.

a multi-- the free head 11 is also generally rect gular in cross section and i thatis lined .with a pair of flangediannnlarbushings; 28f

and an annular resilient gasket 29; The; flanged annular; bushings 28 extend inwardly from opposite sides ofthe front cylinder head 11 and clamp the annular resilient gasket 29 therebetween so that the forwardfendl of the The snap rings 38 prevent longitudinal movement of the elliptical pistons 37 and the O-rings provide fluid tight seals between the opposite sides of the pistons but yet the means for mounting the elliptical pistons the common piston rod is such that the elliptical pistons are floatingly mounted. Thus, the elliptical pistons are free to turn with respect to the common piston rod. This is particularly important in that free sliding movement of the piston rod is always insured even if the individual cylincommon piston rod 21' isaccurately guidedfforrlongitu- 10 der wall elements 13 and cylinder spacer elements 14 are dinal movement while the annular gasket 29 provides the requisite fluid tight seal. An annular-cover plate 30 is mounted on the forward face of the acne cylinder head. 7 i

The front cylinder head has a right 'angled return pas:

not perfectly alignedtsince the floatingly mounted pistons will always align themselvesrotativelywith the elliptical inner surfaces 17 of the cylinder wall elements 13. It should be apparent that this feature greatly facilitates sageway 31 communicating betweenthe rear surface and the construction and assembly of the multiple piston elthe side edge thereof to provide a means for supplying fluid for returning the cylinder to its initial or ietractedi' position after actuationthereof. i

It will be noted that all of the palrts' described are liptical fluid cylinder and also allows proper operation and free movement of the piston rod.

As set forth above, in some instances it is desirable that any turning or rotativemovement of the commonv piston characterized by their extreme simplicityand that the 20 21 about its longitudinal axis be prevented in order that main cylinder portion isa'ssemblcd from 'a' plurality of identical wall and spacer elements wherebythe multiple piston elliptical fluid cylinder may be easilymanufactured and assembled at a low cost. In the'illnsti ated embodi the driven member attached to the protruding end of the piston rod remainsin proper position without the necessity of ways, etc. Thefluid cylinder of the present invention, is ideally suited for such usesbecause the elliptical ment of the invention the main cylinder portion is shown 25 pistons are non-circular' and provide an excellent'antito comprise four cylinder wall elements and three cylinder spacer elements arranged in stacked alternating fa'shion but it should be clearly understood that more-or less p of these elements maybe employed depending upon the;

turn me'ans. To accompish this end one of the'elliptical pistons 37 is rigidly attached tothe common piston rod 21 as, for example-by masses; pin 41 as shown in Figure 1 of thedr'awing; Onlyone'of the'elliptical pisforce applying capability required of a cylinder for any tone is rigidly mounted on the-piston rod'to preventturngiven application. The means employed for' guiding the common piston rod including the apertures19 and 'O rings 20 in each of the spacer elements and the bushings 28 and annular gasket 29' in the front cylinderhead+is particularly advantageous; since the pistonrod is posialignment of the various cylinder elements.

tively guided for longitudinalimoveme'nt atspace'd points throughout its length and the'required fluid tight seals ing thereof while the rest of the pistons are floatingly mounted for rotative movement. '"In thisfmannerrotation of the piston rod is prevented while yet all butone of the; pistons are free to turn to compensate for any mis- By employing the arrangement above described for mounting the pistons on the commodpiston rod it is possible 'to eliminate the notches 17 on the sides of the cylinder spacer elements 14, the flange 24 on the "rear O-rings, bushings and a gasket whereby the manufacture 40 cylinder head 12 and the notch on the frontcylinder head of the multiple piston elliptical cylinder is greatly facilitated, i "11 t.

Theassembled maincylinder portion 10 in cooperation with the front andrear cylinder heads 11 and 12 and the 11. These members would be provided with flat planer end surfaces against which the ends of the cylinder wall elements would be tightly held by the. plurality of tie rods 16. Such construction; whichis greatly simplifiuid tight sealsbetwen the spacer-elements 14 and the fied and inexpensive, is possible since. the fioatingly piston rod 21 forms a plurality of fluid-tight, axially aligned and spaced elliptical -fiuidchambers 33. Received and guided within each of the elliptical fluid chambers 33 is an elliptical piston 34 ("see- Figure 3 of the mounted pistons will compensate for any misalignment between the various axially stacked cylinderpelemcnts.

The common piston rod 21 is tapped. axially from the rear and thereof throughout'aiportion'of'itsi'length to drawing) which is mounted on and movablewith the provide the longitudinally extending passageWaySQ-and common piston rod 21, Each of the elliptical pistons has a seating groove running around its elliptical outer periphery into which is seated a resilient and-deformable O-ring type seal 35 that pro'vide'sia fluidtight seal betweeni V I w V the elliptical inner-surface 17 of the'cylinderwallele- Thusyan inlet means, 'compnsmgthe'mlet passageway merit associated therewith and-the opposite sides'of Ithe" a .seat for-resilient and deformable O-rings 37 thereby is also tapped normally at spaced points along its length to define transverse passageways? 40communicating be tween the passageway 39 and the compartm n s in the 25,1 passageway 39 and one: of: the transverse passagedefiningfluid tight seals betjweenthe oppositesides. of the 59 o mon piston. rod formsa P0 9 Of ih nl ea elliptical pistons and the common pistonrod 21.: Thus;

each of the chambers 33 is divided into forward and rear:

fluid tight compartments by the-elliptical piston 34 due to the O-ring type seal 35 and O-ring 37 carried thereby.

Each of the elliptical pistonsin mountedon the common piston rod by a pair of snap rings 38 received within suitable axially spaced and circumferentially extending grooves machined on the piston rodso that the elliptical pistons are always retained in their correct relative longi-- tudinal. positions. The means providingth'e'fluid-tight seals between the cylinder wall elements, the" piston-rod and the elliptical pistons and the means an {mounting thepistonsv on the piston rod 'are character by their extreme simplicity in :manufacture and asse lx' 1 ,1 av

and this precludes the necessity of complicated and expensive machiningand boringpther portion ofthe fluid cylinder. As'previionsll' desc ibed, the o r 7 In the operationpfthe'multiple'piston-ellipticalffluid cylinder described :above,; fluid under; pressurei--is supplied to theinlet passagewayilsand this fluid will be carried to therear compartment ofeachof'the chambers 33 via this passageway-and the passageways 39 and 40 in the common piston The fluid under pressure 15 williexert a force on each er the ellipticalpistons theref chambers 33' to the rear: of thcl' elliptical pistons-34.

Wag,

by causing forward movement of the same and the piston rod to which these members are attached. One of the most important aspects of the present invention is the provision of a multiplicity of elliptical pistons wherein the individual pistons provide'large areas for the fluid under pressure to act against and this, along with the number of elliptical pistons, allows the application of very high forces to the piston rod and the driven member connected thereto while yet the entire fluid cylinder is extremely small, especially in its thickness dimension. Such a fluid cylinder is well adapted for applications requiring a high force applying fluid cylinder where the space for mounting such a cyl nder is restricted due to other considerations.

To return the piston rod and the elliptical pistons to their original or retracted positions the passageway 25 is connected to tank and fluid under pressure is supplied to the return passageway 31. Fluid is admitted through this last mentioned passageway to the forward compartment of the first chamber 33 thereby causing reverse movement of the piston rod and elliptical pistons with the fluid in the rear compartments of the chambers flowing to tank through passageways 40, 39 and 25. It will be noted that on the return stroke fluid is admitted only to one of the forward compartments and this allows conservation of the actuating fluid, such as air, for example. Of course, if desired, fluid under pressure can be supplied through suitable passageways to all of the forward compartments for returning the piston rod and elliptical cylinders to their original positions.

When fluid under pressure is supplied to only one of the forward compartments of the chambers 33 the other forward compartments are in communication with the atmosphere through the relief passageways 22 and these passageways provide a means for relieving any pressure or exhausting any fluid within these forward compartments of the chambers due to failure of the seals between the elliptical pistons and the wall elements and the piston rod or for any other reason. In the case where fluid under pressure is supplied to all of the forward compartments these relief passageways would be blocked or upon enlargement thereof may serve as the additional return passageways.

It should thus be apparent that I have accomplished the objects initially set forth. There is provided a fluid cylinder which, due to the multiplicity of elliptical pistons in combination with the many features of improved construction, is of small size and dimensions but yet has high force applying capacibility. The fluid cylinder shown in the drawing has four chambers but it should be apparent that a cylinder having more or less of these chambers may be constructed by inserting or removing wall elements, spacer elements and the elliptical pistons and providing a longer or shorter piston rod as required. In this manner the resultant multiple piston fluid'cylinder will have the desired force applying capability for any given application.

Many changes may be made in the illustrated embodiment of the invention without departing from the clear teachings thereof. Accordingly, reference should be had to the following appended claims in determining the true scope and intent of the present invention.

I claim:

1. A small size fluid cylinder for applying a high movingforceandadaptedtobemountedinalimited mounting area providing minimum space comprising a. main cylinder portion, a pair of cylinder heads at the ends of said main cylinder portion, said main cylinder portion comprising a plurality of identical axially elongated annular and generally elliptical wall elements, said wall elements each having an elliptical internal surface, a plurality of identical relatively short axially extending spacer elements, said spacer elements being positioned between adjacent ones of said Wall elements in axially aligned relation with respect thereto, the number of alternating and axially stacked wall elements and spacer elements being selected to provide an elliptical fluid cylinder having desired force applying characteristics, said spacer elements, said wall elements and said cylinder heads defining a plurality of axially aligned and spaced elliptical fluid chambers, a common piston rod extending axially through said spacer elements and at least one of said cylinder heads and movable axially with respect thereto, a plurality of elliptical pistons mounted in axially spaced relation on and carried by said common piston red, one of said elliptical pistons being received in each of said elliptical fluid chambers and having fluid sealing contact with the elliptical internal surface of the Wall element associated therewith to divide each of said elliptical fluid chambers into a pair of expansible and contractable fluid tight compartments, means to supply fluid under pressure simultaneously to one set of the like ones of the pairs of expansible and contractable compartments to move said piston rod under a high force, said means to supply comprising an axial bore in said common piston rod, a plurality of radially extending and axially spaced passageways in said piston rod communicating with at least a portion of said one set of said like ones of said compartments, inlet means communicating with at'least one of the other set of the like ones of said compartments for supplying fluid under pressure thereto to return said piston rod, a plurality of tie rods extending between said cylinder heads for maintaining said cylinder heads, said wall elements and said spacer elements in assembled relation, and said tie rods being disposed adjacent the ends of the major transverse axis of said elliptical fluid cylinder whereby the width of said elliptical fluid cylinder along the minor transverse axis thereof is maintained at a to allow mounting of said elliptical fluid cylinder in a limited mounting area.

2. Apparatus according to claim 1 further comprising means mounting said elliptical pistons on said common piston rod, and said means mounting preventing axial movement of said pistons with respect to said piston rod but permitting relative rotational turning movement between at least a portion of said elliptical fluid pistons and said piston rod to permit individual registry and alignment between said elliptical fluid pistons and the elliptical fluid pistons and the elliptical wall elements associated therewith.

References Cited in the file of this patent UNITED STATES PATENTS 1,436,177 Krause Nov. 21, 1922 1,658,962 Aikens Feb. 14, 1928 2,546,596 Haines Mar. 27, 1951 2,661,599 Folmer Dec. 8, 1953 2,753,847 Reynolds July 10, 1956 

